Framing, the practice of constructing a skeletal shape of a functional unit out of elongated, strong and relatively unyielding base materials, is enjoying widespread use in today's industrialized, mechanized and technocratic society. The advent of new and durable materials from which framework members can be constructed has further enhanced the use of non-integral, i.e., frame not formed as part of the plane surfaces, and non-unitary framework. Where earlier metallic frame members had to be bolted or welded to each other to achieve a desired network, it is now possible, using materials such as polyvinylchloride (PVC) plastics, to cast such frames in a single piece. Such an alternative, however, is not always the desirable one. Oftentimes, a particular application might best be realized by retaining the traditional member-fixed-to-member means for building the framework. By constructing the individual members of the new materials, not only can their usefulness be exploited, but the versatility of the more traditional and basic frame making technique is retained.
In my practice of constructing various frameworks, especially using frame members composed of PVC materials, I have often found myself impeded by the lack of an easily assembled, strong and reliable means of connecting the frame members. The materials with which I have chosen to work, particularly PVC tubular frame members, do not lend themselves to easy interconnectivity save for actual cementing, a process requiring special cleaning and preparation in conjunction with use of a certain costly solvent-cement. The more traditional joining means such as bolting or cementing, analogous to metal welding, are cumbersome, time-consuming and limited in application. Further, and most importantly, they require the use of extra parts, additional equipment, and all to often, two or more persons to build a desired structure. Frame members which contain joining apparatus, although functional and of great utility are, as noted above, limited in their application in that they must be connected to, and in turn connected by, discrete parts at discrete locations.
A considerable advance in the method of connecting frame members was suggested by Endzweig in his patent for CONNECTING APPARATUS FOR FRAME MEMBERS, U.S. Pat. No. 3,982,841, which issued on Sept. 28, 1976. Endzweig suggested a novel means of interlinking various frame members by attaching them at their respective ends to a common ball-shaped receptacle which received a projection from a frame member which was movably secured within the end of that frame member. Apertures within the receptacle received the projections, which were geometric fits to the apertures, from the ends of the frame members. Once the projection of a frame member is inserted into the receptacle, it is rotated to a locked position and a spring-loaded collar, extending from the frame member, snuggly secures the projection within the receptacle. Thereafter, and at differing locations on the receptacle surface, other frame members are attached in similar fashion. Thus, what results from the Endzweig teaching is a structural framework comprised of members each of which has at least one end adapted to fit into a receptacle, as described above, all co-joined through a plurality of such receptacles.
I feel that Endzweig contributed significantly to the field; however, I cannot help but conclude that the use of an additional member, the ball-like receptacle containing a plurality of apertures, is an unnecessary limitation and, with the use of an intricate protruding mechanism and spring-loaded collar, undesirably complex.
Other framework connectors have been suggested, such as that described by Buttgereit's WEDGE CLAMP SCAFFOLD JOINT, U.S. Pat. No. 4,140,414, which issued on Feb. 20, 1979. Buttgereit also employs the principle of connecting one frame member, having an end projection, into a receiving frame member, having therein a key way adapted to receive the projection and means for snubbing the members in a fixed spaced-apart relationship (once the projection is secure within the keyway). Such a means has been employed for years for affixing the rails of a bedframe to the head- and footboards. The method is a good one in that no additional parts are necessary; however, such jointing means are devised to withstand uni-directional forces only and cannot withstand transverse shock or omni-directional forces.
It is with the advantages, as well as the shortcomings of excellent prior art, that I decided to develop a means for interlocking the elongated structural members of frameworks. The frameworks that could use such a joining technique are myriad and run the range of structural frame-works for automobile carrying racks to scaffolds, to bedframes.
It is therefore an object of this invention to develop a means for joining the separate elements or members of a framework while employing a minimum of parts.
It is another object of this invention to provide an interconnected arrangement capable of functioning in a motive or vibrational environment.
A concomitant object of my invention is to develop a connecting arrangement which is simple, easily handled, inexpensive and, in addition to possessing an inherent versatility, safe and reliable.
It is further an object of this invention to develop a frame member joining means which will be integral with the frame members.
Yet another object of this invention is to produce a frame joining apparatus which is not limited to a single connection at any one end of a frame member.
It is still another object of this invention to develop a framework connection which, for the most part, can function without the addition of other snubbing or securing apparatus.
Objects and advantages of the invention are set forth in part herein or may be obvious, or learned by attendance to this disclosure, or practice with the invention.